Scans 21 main-line DXF files (02 평면·종단, 03 본선굴착, 04 본선기타) for header, layers, entity counts, extents, 3D flag and text samples. Strict load failures fall back to ezdxf recover mode and are recorded. Co-Authored-By: Claude Haiku 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01A5Cun3RHQKna9qxE6ybZ4A